An Introduction to Poverty Measurement

Poverty measures convey the number or percentage of people falling below given income amounts, which are intended to represent a level of economic privation and are computed using some factually based measurement of basic needs. The poverty measures discussed in this report-the official U.S. poverty measure and the research Supplemental Poverty Measure-focus on financial resources. A family's income is compared against a dollar amount representing some measure of need, called a threshold, which typically varies by family size and composition. Those with family income less than the threshold are considered to be in poverty, or poor; those with incomes greater than or equal to the threshold are not considered to be in poverty. All members of the same family have the same poverty status. The poverty measures discussed here are financial measures; they do not directly capture the physical, mental, or social effects of being poor. They were developed to accurately measure economic privation rather than to describe the full complement of resources a person or family needs to be self-sufficient. Poverty data are obtained from surveys, and are therefore estimates that have margins of error. Poverty estimates derived from different data sources-even those using the same definition of poverty-will almost always differ. The official poverty thresholds were developed in the early 1960s, and were based on empirical measures of dietary need, on the amount that a family in economic distress might need to spend on food to attempt to meet its dietary needs, and on the spending patterns of families across the income distribution. This information was used to determine what percentage of an average family's budget was spent on food, and in turn, to compute the amounts representing total family income. There has been broad agreement among poverty scholars that the official poverty measure has serious limitations, and decades of research were undertaken to address them. In 2009, an interagency technical working group, convened under the auspices of the Office of Management and Budget (OMB), put forth the Supplemental Poverty Measure to consolidate the research and emphasize not only sound concepts and methodology in the measure's development, but also practicality in the measure's maintenance, computation, and usage. The Supplemental Poverty Measure was not intended to replace the official measure, and it was expected that refinement of the Supplemental Poverty Measure's methodology and data sources would continue. Neither the official poverty measure nor the Supplemental Poverty Measure was established in statute. The Bureau of the Budget and its successor agency, OMB, directed federal agencies to use the official measure for statistical purposes. The directive explicitly stated that the measure was not developed for administrative purposes, and allowed for other measures of poverty to be developed, as long as the data for those measures were distinguished from the official series. For administrative uses, such as determining whether an individual or family is eligible for assistance from a program, a different set of dollar amounts called poverty guidelines is used. Poverty guidelines are different from the official poverty thresholds, are published by the Department of Health and Human Services, and are not used to count the poverty population. However, any program that relies on counts of the poverty population, such as for formula grants, uses the official poverty thresholds and not the guidelines.